Cooling of internal combustion engines is commonly achieved by way of a cooling system that includes a radiator that receives a coolant fluid flow from the engine and removes heat energy there from. The coolant fluid is then returned to the engine, absorbing heat energy there from, and thereby cooling the engine prior to circulating back to the radiator. Additional engine components, however, may operate more efficiently when cooled with coolant fluid that is within a different temperature range than the temperature range of the coolant fluid circulated back to the engine.
One example of such a cooling system is described in U.S. Pat. No. 6,997,143. In the cooling system in U.S. Pat. No. 6,997,143, a radiator receives a liquid coolant from an internal combustion engine via an inlet section. A portion of the liquid coolant received from the engine may be directed by the inlet section to a by-pass section, where no substantial heat transfer occurs, and then discharged from the radiator. A portion of the liquid coolant received from the engine may be directed by the inlet section to a heat exchange section, where heat energy is removed from the liquid coolant flowing therein. After the temperature of the liquid coolant is thereby reduced, the coolant fluid flow may then be discharged from the heat exchange section (i.e., discharged from the radiator) and returned to the engine. The inlet section may direct variable amounts of coolant fluid flow to a by-pass section and/or to a heat exchange section integral to the radiator, thus varying the volumetric flow rate through both the by-pass section and the heat exchange section. By allowing for variable amounts of liquid coolant to be passed through to both the by-pass section and the heat exchange section (and thus increasing or decreasing the volumetric flow rates there through), the cooling system described in U.S. Pat. No. 6,997,143, may be controlled to discharge liquid coolant that has been cooled to different temperature ranges, depending on current cooling requirements of the internal combustion engine.
The inventors herein have recognized numerous issues with the above approach. In particular, at any given time, the cooling system of U.S. Pat. No. 6,997,143 allows for only a single coolant flow at a specific temperature to be discharged from the heat exchange section. This necessitates that multiple thermostats and/or coolers must be located downstream (i.e., in parallel), of the radiator if multiple liquid coolant streams are to be delivered to the engine and other engine components to facilitate more efficient system-wide cooling.
In one approach, to address the above and other issues, a system for cooling an engine is provided. The system includes, a heat exchanger, the heat exchanger having a first heat exchange portion that removes heat energy from coolant fluid flowing therein, and a second heat exchange portion that removes heat energy from coolant fluid flowing therein; a first thermostat integral to the heat exchanger, the first thermostat fluidically and mechanically coupled to at least one of the first and second heat exchange portions; and a second thermostat, integral to the heat exchanger, the second thermostat fluidically and mechanically coupled to at least one of the first and second heat exchange portions.
By providing a heat exchanger with multiple thermostats arranged integral to the heat exchanger itself, a more versatile cooling system, capable of discharging multiple coolant fluid streams at different temperature ranges to multiple engine components, may be realized.
Furthermore, in one embodiment, porting between a heat exchange portion and a thermostat in such a system can be integral to the heat exchanger. As such, the number of tubes, hoses, connections and associated leak paths may be reduced. In other words, unlike systems in which multiple heat exchangers are arranged separately, the embodiments of the present disclosure described herein below allow for a more compact, simpler, more reliable, and easier to manufacture engine cooling system. The overall cost of the cooling system described herein may thereby be reduced.